Test 1 Module 1 Flashcards
Building blocks of DNA?
nucleotides
DNA is stored in _____ (organelle) in the _______
chromosomes in the nucleus
Sequence of DNA that encodes a functional product
Gene
Humans are _____ organisms.
diploid
An organism with 2 chromosome sets (2n) are known as
diploid
N for humans is?
23
For diploid cells, chromosomes occur in ________ pairs
homologous
_____ has 1 chromosome set (n)
halpid
Haploid cells are human ______
gametes
Order of cell cycle
G0, G1, S, G2, M
G1 explained
cell growth, synthesis of new proteins, organelles, etc…
S
synthesis phase, all DNA is replicated
G2
gap 2- more cell grwoth, synthesis of new proteins, organelles, etc.
M
mitosis or meisosis- cell divides and several substages
What kind of stem cells continuously go through the cell cycle
Hematopoietic (produce all blood cells)
Neurons and Cardiomyocytes never divide and spend their life in ____ phase.
G0
Is a chromosome a single or double structure?
single
Chromosome is composed of a pair of _____
sister chromatids (dyads)
T/F: a sister chromatids is considered two separate structures that are identical.
FALSE, it is only 2 identical copies making up 1 singular structure.
Metaphase
chromosomes align end-to-end along the metaphase plate (MEET)
Anaphase
sister chromatids separate and go to opposite poles (Think of how the A separates at the bottom)
Telophase
When nuclear envelope forms around chromosmes, and chromosomes decondense (the line on T separates)
Cytokinesis
goes with telophase, and cells divide the cytoplasm to produce 2 daughter cells.
Meiosis
diploid cell divides to produce 4 haploid gametes. (in sexual reproduction 2 haploid gametes unite to create a new diploid organism) (2 haploid make a diploid)
Meiosis I stages
prophase 1, metaohse 1, anaphase 1, telophase, and cytokinesis (pleas enote: meiosis II is the same exceot prophase II starts wth only 1 chromosome set, there is no bivalents or crossing over
Prophase I
chromosomes condense
- homologous chromosomes synapse to form a BIVALENT
-crossing over occurs between non-sister chromatids
-chromatids attached at crossover points called chiasma
Metaphase I
bivalents align end-to-end along the metaphase plate
anaphase I
Homologous chromosomes separate to different poles of the cell
Telophase and cytokinesis
chromsomes decondense
nuclear envelope reforms
cytoplasm is divided to produce 2 haploid cells
Gametogenesis
spermatogenesis and oogenesis
Spermatogenesis
occurs in the tested, production of sperm cells
Begins at sexual maturity and occurs continuously throughout the male’s life.
(specialized sperm like cells- spermatogonial cells)
- divide every 16 dayes and produce spermatogonial cells (this will undergoi mitosis) and primary spermatocytes
OOgenesis
occurs in ovaries,
primary oocytes begin meiosis before birth and halt in prophase I
- at sequal maturity one pirmary oocyte resumes meiosis each menstrual cycle
-It compketes meiosis I to produce a secondary oocyte and a polar body
The secondary oocyte halts at metaphase II and is released from the ovary. Meiosis II only completes if the oocyte is fertilized (otherwise it never completes)
An abnormal number of chromosomes occurs more frequently in ______
eggs cells
Why does chromosome number abnormality occur more frequently in egg cells?
Though to be related to the extended time that gametes are arrested in meiosis
Chance increases with maternal age though remains relatively low up to 45+
New mutations are more common in ______
sperm cells, because mutations are introduced during DNA replication. Male germ-line cells divide continuously so, there is mreo opportunity for new mutations to be introduced.
Chance increases with paternal age.
